Transmission



R. CHILTON TRANSMISSION Feb. 18, 1947.

Filed June 23, 1943 3 Sheets-Sheet l INVEN OR I ROLAND JHILT ON. I

ATTORNEY Q Feb. 18, 1947. R CHUQ 2,416,154

TRANSMISSION Filed June 23, 1943 3 Sheets-Sheet 2 INVENTOR ROLANDCHILTON.

-i- BY Ai'TORNEY Pat ented Feb.

TRANSMISSION Roland Chilton, mogewooa, N. J., assignor to WrightAeronautical Corporation, a corporation of New York Application June 23,1943,- Serial No. 492,165

9 Claims. (01. 714-330 This invention provides novel means for providinga multiplicity of torque and speed ratios betweendriving and drivenshafts. jective of the'invention 'is' to provide for very rapid shiftingin order to minimize or eliminate the power-off interval characteristicof conventional synchro-mesh shifts. In these devices, an appreciabletime interval is needed to produce the synchronization of the gears ortooth-clutches to be engaged, during whichinterval the engine or powermeans is conventionally unloaded by disengaging a friction clutch {andwould race to excessive speed unless simultaneously reduced to zeropower by throttling or switching off. During this conventional power-offinterval, heavy slow speed vehicles, such as tanks, are apt to stallbefore the shift from first to second gear, for instance, can becompleted. Such vehicles may be, accordingly, limited to first gearalthough capable of negotiating the conditions in second gear if a quickshift could be made without the excessive loss of vehicle speed, whichisovercome in this invention.

The invention provides a. series of gears referred to by the ordinalnumbers first, second, third, fourth, etc., and the quick shift functionis, in part, attained through the use of two sets of friction andtoothed clutches, onefset serving the "ddd numbered and the other the"even numb'ered gears. In normal running, with one clutch I systemengaging an odd" gear, for example, the

friction clutch of the other system is disengaged and the associatedtoothed clutch is intermediate the next higher and lower even gears ofthe system. The toothed clutches have synchronizing devices and thedisengaged toothed clutch can, according y, be synchronized and engagedwith a higher or lower gear while the power flow continues through thepreviously engaged system. In other words, both of the toothed clutchesmay be engaged at once because only one of the friction clutches can beengaged at atime. After the synchronizing and engagement ofany new gear,the clutch actuating pressure is rapidly transferred to the frictionclutch of such newerated friction clutch having anovel dispositionwherein the effects of centrifugal forces on the A prime ob-- hydraulicfluid ixblala nced and where "sludge troubles are overco In conventionalclutches, as applied by hydraue as follows:

- lic pistons and cylinders rotating with the clutch,

centrifugal force exerts hydraulic pressure on the piston even when thefluid pressure source is cut off, thus preventing disengagement untilthe clutch purges itself of fluid by leakage. For quick disengagement afast rate of leakageis required but this involves continuous oil flowthrough the cylindervcavity behind the piston while the clutch isengaged. Thus, the entire oil'quantity in the lubricating system may berepeatedly circulated through the clutch. It has been found that highspeed clutches of this. character comprise effective centrifuges causingthe particles with which the actuating oil is often contaminated(especumulated semi-solid deposit which may jam the clutch actuatingpiston against retraction.

In the present invention a double-sized piston is used whereby thecentrifugal effects on the oil are exactly balanced and the conventionalleak- I age vent is eliminated so that there is no intentional flow ofoil through the clutch cylinders and, accordingly, the operating actionis merely to displace the small oil quantity behind the piston once foreach shift. The amount of sludge in this small oil quantity isinsignificant as compared with the case of the conventional ventedclutch through which the entire quantity of oil in the system (which mayinclude an engine) is slowly circulated thus acting continuously as acentrifugal separator. 'An associated advantage of the new clutchdisposition is'that full hydraulic pressure is available to overcome anysticking tendency of the piston thus insuring prompt disengagementand/or transfer of drivin load.

The invention includes a series ofside-by-side gears having similarinternal clutch teeth through which a pair of toothed clutch membersshift successively from one gear to the next, 1. e., the tooth clutchesare organized to engage and disengage a specific gear from and to eitherside thereof. To permit this through-shifting action, special.synchronizing devices are provided which permit any gear to be engagedfrom either side of its clutch teeth and which allow the engaging memberto travel on through and beyond the gear last engaged. I

Other objects of the invention will be obvious from or will be pointedout in the following deplate 38.

' Figures 1 and 2 are diagramatic, omitting certain constructionaldetails so as to simplify the drawings for clearer illustration ofessential elements Fig. 8 is a fragmentary enlarged axial sectionshowing the synchronizers; i

Fig. 9 is a section on the line 99 of Fig. 8;

Fig. 10 is a developed fragmentary section on the pitch line of thesynchronizer clutch'teeth; and

Fig. 11 is a fragmentary II-II of Fig. 8.

Referring first to Fig. l, Ill designates a clutch housing member, whichmay be the flywheel of an associated engine, mounted on the crankshaftthereof (not shown) by the hub I2. The flywheel section on the linemembers comprise similar opposed annular cylinders'in which is fitted astepped annular pismember 50. Leftward extensions of these shift membersengage control collars 55 and 58 having camfollower stubs 52 and 54engaged in shift.- ing cam grooves 60 and 62 formed on the exterior ofthe cam-valve assembly 34 as shown. In the case of the shift member 50,actuated by the control collar 56, the connecting elements have to passthrough and beneath the shift member 48 which is, accordingly, slottedto pass connecting bars 59 (best seen in the end views of Figs. 7 and9). These bars must rotate with the outer shaft 44 and shift member 48and, accordingly,

[they have a rotatable connection indicated at or clutch housing II) hasa cover I4 and these ton I5 including a clutch pressure plate I5. Saidpiston-pressure plate member is provided with sealing rings I8 and 20,as shown, and an axially slidable spline drive I! is provided between Ithe piston I5 'and theclutch housing. Passages 22 and 24 communicaterespectively with the right and lefthand sides of the piston and withcollecting grooves 26 and in the hub I2. This hub operates in a bearing(not shown) to which oil lines indicated by the dotted lines 30 and 32supply oil pressure under control of the comvalve assembly 34 isarranged to supply oil pressure to either the oil line 30 or the oilline 32 while venting the other to atmosphere,'as later to be described.It will be obvious that whenever such oil pressure is applied throughducts 32 and 24, such pressure will devolve on the lefthand side of thepiston I5, moving itover to the position shown. The pressure-plate l6cooperates 5| with the member to permit different speeds of rotation.The shifting cam grooves '50 and 52 are shown in developed view in Fig.3 and will be seen to comprise helical shiftin elements 64 and 55interspaced with parallel or dwell elements 68 and Ill. -In Figs. 2 and3 the cam 34 has been rotated from its first speed position to a neutralposition in which both sides of the piston I5 are vented to theatmosphere. .The pro-. files and relationships of the two cam tracks issuch that the two toothed clutch members 48 and 50 do not movesimultaneously butin predetermined sequence, and' this sequence isfurther correlated with the valving functions for the actuation of thefriction clutches, as follows:

The cam-valve assembly 34 is mounted on a stationary valve member I2,Fig. 6, having three alined holes E, P and O of which the hole P is apressure inlet connected to an engine driven pump I4 (F g.2) by a lineI3 while the holes E and 0 connect to the lines 30 and" 32 feedingrespective sides of the clutch piston I5, as previously described; Theholes E, P and 0 are indicated by crosses in Fig. 3 whichalso indicates(in dotted lines) valve ports 16 and '18 cut in the interior ,of the camand seen also in "Figs.

'4 and 5. These ports serve to connect, at the proper time, the hole Pto either the hole' E or O and thus supply pressure to the respectivesides of the clutch piston I5. At the same time, the other side of thepiston I5 is vented to the atmosphere by-narrower venting ports 80 and82 which communicate with radial holes 84 drilled through the cam topermit the oil displaced from the inactive side of the piston to escapeas. the piston moves over from one position to another. The cam-valveassembly 34 is moved in shift increments of of a turn corresponding tothe circumferential spacing of the valve ports and cam profile elementsand to thegear shift increments of the toothed clutches 48 and 50. Suchincremental shift rotation of the cam may be I produced. by any desiredmanual means or by reciprocally with separate driven clutch plates 36and-38 arranged on eitherside. In the posi-.- tion shown in Fig. 1, thecam-valve assembly 34 has applied pressure to the lefthand side of thepiston I5 through'the ducts 24 and 32 thereby outer shaft 44 is atoothed clutch shaft member 48' and similarly shiftable along splines onthe inner shaft 46 is a second toothed clutch shift automatic shiftingmeans later to be described,

the operation of the parts so far described being the same for automaticas for manual shift.

Referrin'g'again to Fig. 1, a plurality of gears I, 3, 5, 2, 4, 6 willbe seen arranged "in axial series in the order written and each of thesegears has identical clutch teeth engageable by the clutching shiftmember 48 in the case of gears I, 3 and 5 and by the shift member 50 inthe case of gears 2, 4 and 5 (the latter comprising a direct driveconnection). The numbers assigned to these gears are the ordinal numbersof their relative gear ratios, I representing the lowest driven speedand 6 the highest (or direct drive) speed. These relative drivenspeeds'are obtained is always through the which meshes with a gear 88which is connected. for forward drive, to a final drive shaft 88 througha shiftable spline clutch 82. Reverse drive m this are obtained throughradial pinions 84 end layshaft gear 8-18 6 54 tor the speed drive ratios1 to 6 are indicated .111 Fig. 3 in dotted lines at 52a, 54a to 52/,54!,

mounted in fixed bearings (not shown) and engaging a gear "which,accordingly, rotates in reverse direction to the gear 88. This gear 88may bedisengaged and the gear 88 engaged by 8 moving the spline member82 to the right whereby this particular embodiment comprises six forwardand six reverse speeds. It will be noted that the gears of first,second, third, etc., ratios are not arranged axially in simple ordinalseries but that the gears of the "odd numbered ratios venientlydistinguished as belonging to the "odd" and even gear shift systems andthe symbols and E have, accordingly, been used on the drawings toquickly distinguish the elements belonging to these respective systems.

In the neutral position of the cam as illustrated in Fig. the cam hasthe lower end of' its profile engaged with the respective cam followerstubs 52 and 54. In this position of the cam, port holes E and O andtheir associated ducts 38 and 32, respectively, are connected torespective vent ports 82 and 88 whereby both' sides of the piston I arevented to the atmosphere and the piston rotates freely between theclutch plates 36 and 38. Also in this position of the cam the toothedclutch member 58 is out of engagement with and immediately to the leftof gear 2 (the first even gear) and the toothed clutch member 48 is inengagement with gear I (the first odd gear) although obviously no driveis being transmitted therethrough because of respectively. 1

Movement of the cam-valve assembly to the second speed position firstmoves the toothed clutch member 58 into engagement with the gear 4 2without yet moving thealreadyenga'ged member 48 and, when the engagementwith gear 2 is complete, further continued movement of the cam willreverse the hydraulic clutch pressure on the piston l5 thus quicklymoving the pressure plate [8 to the'left, disengaging the odd clutch 38and engaging the even clutch 88 thereby promptly transferring the drivefrom the engaging member 48 to the engaging member 58 (but only. afterthis member has been fully engaged). The shift increment to second speedis completed by further movement of the cam during which the previouslyengaged selector member 48 is moved to the right into neutral position(but without other change). The camvalve' assembly 34 for each shift ismoved through (in this case) one-seventh of a turn to com plete thiswhole cycle of events for any shift.

It will be seen, for example, that we now have the engaging member 48intermedaite gears I, 3

while the member 58 is engaged with gear 2 so that should be cammovement be retracted over 4 the first shift just described, the partswould be the disengagement of clutch plate 36. If desired,

the lower end of cam groove 62 could be inclined so as to move thetoothed clutch member 48 out of engagement with and to the left of ingmembers 48 and 58 but moves one of the venting ports 82 out of alinementwith hole E in valve member 12 and alines an adjacent vent port 82therewith. At the same time this movement, of cam 34 moves one of theventing ports 88 outof alinement with hole 0 in valve member 12 andalines one of the ports 18 with holes P and 0 in this valve member toapply fluid pressure through ducts 32, 24 to the left side of piston l5,as illustrated in Fig. l. Thereupon the piston pressure plate It engagesthe clutch plate 36 to provide a drive through the outer shaft 44,toothed clutch member 48 and first speed gear I. The relative positionsof the cam grooves 88 and 62 relative to the cam follower stubs 52 andrestored to the position shown. On the other hand, should anotherincrement of cam shift movement be desired (the increment into thirdgear), it will be seen that the appropriate "odd engaging member 48 isin neutral ready for movement into this gear. In other words, when anygear (except the end ratios 1 and 6) has been engaged by the appropriateshift member, the other member is located in neutral between the gearsof ordinal numbers next above and below the engaged gear and istherefore ready for shifting into the next higher or lower gear, asdesired, by forward or backward rotation of the cam-valve assembly. Itwill be further noted that the entire sequence of shifting events iscorrelated by the cam tracks 88 and 62 and the associated valve ports,18, 88 and 82, these be ing pre-formed in the cam-valve assembly 34 togive the appropriate timing and sequence as described. I

In the diagrammatic illustration of Fig. l, andin order to simplify theshowing, the fneutral" spaces between the clutch teeth of adjacent gearsappear empty. Actually, synchro-mesh devices are disposed in thesespaces but these could only be clearly shown in the enlarged views ofFigs. 8 to 11. These synchro-mesh" devices prevent the engagement of theshift members 58 and 48 with a gear until said devices have producedsynchronization, and in this respect they may involve the usual delay inengagement referred 'to in the introduction. However, it is an essen entspeeds as permitted by the friction clutch or,--

ganizationwhereby only one clutch is'engaged leaving the other alwaysfree, as previously described. Upon completion of synchronizationandengagement of the new gear, the hydraulic system transfers the clutchload to the friction 7 clutch of that gear simultaneously releasing thefriction clutch of the previously operating gear so that the shiftmember thereof may be moved to neutral by the cam, all as previously.described.

Recapitulating; the sequence is:

(a) Synchronizing a new gear ratio. (b) Engaging the same. Release ofthefriction clutch of the previous ratio. I (d) Engagementof the frictionclutch of the new ratio.

' (e) Movement of theshift member of the previous ratio to neutral.

Only the first operation (a) absorbs any appreciable time, butregardless of how long this synchronizing interval may be, the vehicleis being continuously driven through the driving system of the previousratio and thus the necessary synchronizing time does not involveany.correspond-' ing power-ofi period which is one important distinctionbetween this invention and convention- 'al synchro-mesh systems.Actually, the only power-off interval will be that required for themovement of the piston I (approximately 1 which transfers the drive fromone ratio'to another by transfer from one friction clutch to the other(the shift or selector clutches of both ratios being simultaneouslyengaged at this point). It is intended that this ratio transfer from onefriction clutch "to the other shall be so rapid that the engine maybemaintained at full power without excessive acceleration. The inertiaof the flywheel I0 will control the degree of acceleration and it ispointed out that engine power is stored in the flywheel during any suchacceleration and is available for extra torque when the friction clutchtransfer occurs, as is specially desirable in the caseof an up-shift. Inthe case of a downshift, such acceleration tends to synchronize thefriction clutch to be engaged, which is turning atfaster-than-engine-speed when (down shift) synchronizationof theassociated shift member is complete.

The synchronizing devices are shown to en larg'ed scalein thefragmentary views Figs. 8 to 11, inclusive. Referring first to Fig. 8,the gears l, 3, 5, 2', 4, 6 are seen to have coned clutch faces 98formed on both sides (at least as far as the intermediate gears areconcerned), and spaced intermediate the adjacent gears for-cooperationwith said .coned clutch faces. are. identical synchronizer memberscomprising a central element I00 having internal teeth I02 which theteeth of the selector clutches 48 and 50 mayengage and/or pass through.Externally, the synchro teeth of the selector member in question to onev side of their backlash falls to zero'and,,accordingly, the shiftingeifort is able to force the selector teeth 48 to pass the bevelledshoulders I06 on the teeth of the side plates I04 and engage with theteeth of the synchronized gear.

In Fig. 8 the lefthand or odd" selector clutch 48 is shown in mesh withthe teeth of the gear I and bearing bands I08 are arranged on each sideof the selector teeth so that one of these is centralizing and carryingthe adjacent synchronizer member I00 in virtue of a close running fit,between said band and the-tops of the synchronizer teeth. This bearingband normally carries the adjacent synchronizer member so that itrotates with the selector clutch which will next engage it, under whichcondition the synchronizer member is free to float out of any pressurecontact with the associated clutch cones. However, should shiftingmotion be initiatedat the selector clutch 48 (to the right, forinstance) its teeth will, in general, first collide with the teeth ofnizer members have coned clutch faces adapted to engage the coned clutchfaces 98 of. the gears.

Each synchronizer member has secured on either side toothed plates I04(better seen in the enlarged views of Figs. 10 and 11) The tooth widthsof the synchronizer members I00 are narrowed to widen the tooth spacesto allow some rotational clearance or backlash with respect to theengaging teeth of the selector members 48 and 50 but, as seen in thedevelopment of Fig. 10, the side plates I04only have normal backlash ortooth space width adapted to pass the teeth of selector members 48 and50 on alignment. In other words,

. the plates -l04 comprise shoulders I06, which may be slightly bevelledas shown, which shoulders act: as stops so that whenever there issynchronizing torque'from the friction cones 98 forcing the teeth ofselector members 48 and 50-to one side or the other of their backlashwithin the the unitarily rotating synchronizer member as the teeth willnot usuallyhappen to be lined up.

The shift pressure, however, will force the synchronizer cone intocontact with the cone of the gear being approached, which gear istraveling at different speed to the selector. Such contact with thefriction cones will rotate the synchronizer memberrelative to theselector (by rotation on the band I08) and instantly the next gear toothspace is aligned, the selector will pass on into the synchronizerteeth, 1. e., the condition shown in Fig. 8 for the righthand selector50.

The inner diameter or tops of the synchronizer teeth are provided withcircumferential V notches IIO with which cooperate radial-plungers I I2urged outwardly by a spring ring I L4,. Accordingly, these spring-urgedplungers expand into the notches thus centralizing the teeth 48 betweenthe side plates I06 and'providing for a necessary initial axial forcewhereby continued axial shifting movement carries the synchronizer intoinitial contact with the friction cone of the gear to be meshed. Suchfriction engagement immediately generates synchronizing torque betweenthe teeth of the selector and the synchronizer, forcing these teeth tooneside of their backlash as shown in Fig. 10, so that further axialshifting motion is balked by the shoulders I06, as pr viously described.Such balking action maintains until the parts are synchronized,whereupon the synchronizing torque ceases and the selector tooth 48 isfree to slide over the sloping shoulders I06 and through the appropriateside plate lo l-into engagement'withthe synchronized gear.

Novel features of this inhibitor synchronizer device reside in providingan organization which permits through-shift of the selector along aseries of ears.

mesh the several gears from either side and that the selectors furthermay. approach the several.

It will be noted that this organization permits the selectors toapproach andthe quadrant m pair of gears each of which, accordingly, isonly engaged and disengaged from and to one side and there is nooccasion for the selector to be able to pass on serially through thegears or syn- I chronizers. In short, the conventional systems have beendeveloped to suit a gate" shift where each shift clutch serves only twospeeds, in contradiction to the present straight-through or serial shiftwherein one selector may serve and pass through any, desired number ofgears. The provisions for such a through-shift and one wherein a pair ofconcentric selectors serve any desired plurality of gears through a pairof reciprocally engageable concentric friction clutch elements areimportant features .of the present invention.

The cam-valve assembly 34 is rotated througha pinion I I6, engaged by aquadrant gear I I8, the quadrant including notches I20 spaced onegearshift increment apart and engaged by a roller I22 carried in aspring loaded latching plunger I24, mounted on a rigid rod I28. Thequadrant I I0 swings on a shaft I28. which may be operated by a suitablehand lever connection I30, in the case of manual shift. The profiles ofthe notches I20 are such that, when suificient shifting pressure hasbeen applied to the quadrant I I8 to overcome the restraint of thespring plunger I24, the

quadrant will tend to snap smartly to the next gear station, except asthe shift may be temporarily balked by the synchronizing means alreadydescribed, which act conventionally in the respect that the.synchronizing force is proportional to the shifting pressure applied tothe balking ring.

Fig. 2 also shows an automatic hydraulic shifting system including theprimary engine driven pump 14 which, in addition to supplying clutchactuating oil to the automatic valving mechanism (previously described)by the duct 13, may also deliver, through a connection I32, to theintake side of a pump I34, which is driven from the final drive side ofthe transmission so as to run at vehicle-proportional speed.Alternatively, pump I34 may receive oil directly from a source ofsupply.This pump delivers oil through a duct I36 to the bottom of a hydrauliccylinder I38, past a tapered metering escape valve I40, operated by aSylphon bellows I42, subl 10 will be snapped upwardly rotating the cam34 and initiating an up-shift, until the balkingring of the associatedsynchronizer is encountered, whereupon the motion is temporarilyarrested while the shift pressure devolves upon the synchronizer thusproducing synchronization, whereuponiie shift is promptly completed byelastic recovery of the spring. I 60.

Similarly, as the vehicle-slows down in speed, and

therefore the pressure from the pump I34 de-' creases so that less ofthe pressure of the spring I60 is balanced by the spring I58 and when asufficient degree of unbalance exists, the restraint of .the springdetent roller I22 is again overcome and a down-shift is initiated. Therate of leakage at the valve I40 determines the degree of pressuregenerated by the pump I34 for any given vehicle speed and the positionof this metering valve I 40 is biased by the pressure existing in theSylphon bellows I42 which is subject to pressure from the intakemanifold of the associated engine. This pressure is closely proportionalto the instant torque being developed by the engine so that the controlis urged towards an up-shift responsively to increasing vehicle speedand towards a downshift by increasing engine torque. The ratio of thesetwo opposing urgencies, i. e., the automatic shift characteristics ofthe transmission with respect to the vehicle speed and engine torque maybe varied over a wide range by adjustment of the following elements:

(1:) The spring I 60 which urges the shift towards first gear. Increasedspring pressure adjustment will delay the up-shift with respect tovehicle speed.

(1)) Adjustment of the arm I48 to change the I In combination, theseadjustments and/or controls may be utilized to vary the shiftcharacter-. istics over any desirable range.

It will be seen that when the vehicle comes to rest, the booster pumpI34 ceases to deliver any pressure beneath the piston I50 and,accordingly,

the spring I will by this time have returned the valving cam 34 to theneutral position, the oil ward motion of the piston I50, through aspring 7 I58 against the opposed downward pressure of a spring I 60,adjustable by a nut I62. It will be seen that, with any given setting ofthe leakage valve I40, the pressure beneath the piston I50 will beproportional to the speed of the pump I34,

i. e., to the speed of the vehicle or of the driven shaft of thetransmission. Such pressure will increaseas the vehicle speed increasescompressing the spring I58 and the spring I60 until the force exerted onthe rod I52 is sufficient to overcome the restraint on the quadrant dueto the 3 spring loaded latching roller I 22, at which instant to itsfirst speed position whereupon a drive is cut oil from both sides of theclutch piston I5 whereby both the friction clutches 36 and 38 aredisengaged and the engine may run without driving the vehicle, With thevehicle at rest, the pump I34 delivers no pressure so that a manualcontrol is necessary to shift into first gear. For thispurpose thehandle I30 may be operated to impart initial shifting movement to camv34 through gear I is provided, as previously described, Once the vehicleis in motion, the pump I34 supplies oil pressure and the automatichydraulic shifting mechanism just described becomes operative.

While I have described my'invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstanding my invention, that various changes and modifications maybe made therein without departing from the spirit Orsc'ope thereof. Iaim in the appendedaclaims to cover all such modifications and changes.

I claim as my invention: 1. In a transmission, a plurality of concentricpnested annular gears defining an axial opening about the axis of saidgears, and a plurality'of gears on each of said layshafts, the gears oneach of said layshafts respectively being in mesh with said concentr cnested gears.

2. In a multi-speed transmission, a plurality being axially shiftablewithin said opening for selective engagement of its clutch teeth withand from either side of the clutch teeth of its associated group ofgears, a pair. of clutches alternately engageable to connect the drivethrough one of the other of said gear selector'members, and synchronizermeans between the adjacent gears of each group, each synchronizer meansbeing adapted to prevent shift movement of the associated gear selectormember into engagement with the clutch teeth of each adjacent gear.

5. In' a multi-speed transmission, a plurality of annular gears disposedin s'ide-by-side relation and defining an axial opening therethrough,said gears each providing a difierent transmission speed-ratio and beingarranged with the gears providing the even and odd numbered speed ratiosrespectively grouped together, the gears of each group having similarinternal clutch teeth, and a pair of concentric gear selector members,one for each of said groups of gears, each of said gear selector membershaving a set of clutch teeth and being axially shiftable within saidopening annular. gears disposed in side-by-side relation 4 and definingan axial opening therethrough, said gears each providing a difierenttransmission speed ratio and being arranged with the gears providing theeven and odd numbered speed ratios respectively grouped .together, thegears of each group having similar internal clutch teeth, a pair ofconcentric gear selector members, one for each for selective engagementof its clutch teeth-with and from either side of the clutch teeth of itsassociated group of gears, a pair of clutches alter- Y nately engageableto connect the drive through one or the other of said gear selectormembers, and synchronizer means-between the adjacent gears of eachgroup, each of said synchronizer means having friction means engageablewith the adjacentgears and being arranged to balk shift movement of theassociated gear selector member clutch into engagement with the clutchteeth of either adjacent gear until said frictional engagementsynchronizes said gear selector member with-the gear to be engaged.

of said groups of gears, each of said gear selector members having a setof clutch teeth and each being axially shiftable within said opening forselective engagement of its set of clutch teeth withfth'e clutch teethof its associated group of gears, and a pair of clutches alternatelyengageable to connect the drive through one or the other of saidgear-engaging clutches.

/ 3. In a multi-speed transmission, a plurality of annular'gearsdisposed in side-by-side relation and defining an axial openingtherethrough, said gears [each providing a different transmission;

speed-ratio and being arranged with the gears providing the even and oddnumbered speed ratios respectively grouped together, the gears of eachgroup having similar internal clutch teeth, and a pair of concentricgear selector members, one for each of said groups of gears, each ofsaid gear .selector members having a set of clutch teeth and beingaxially shiftable within said opening for selective engagement of itsclutch teeth with and fromeither side of the clutch teeth of itsassociated group of gears, and a pair of clutches alternately engageableto connect'the drive through one or the otherof said gear selecv tormembers.

4. In a multi-speed transmission, a plurality of annular gearsdisposed'in side-by-side relation and defining an axial openingtherethrough, said 6. In a multi-speed transmission, a plurality of Iannular gears disposed in side-by-side relation and defining an axialdpening therethrough, said gears each providing a different transmissionspeed-ratio and being arranged with the gears providing the even and oddnumbered speed ratios respectively grouped together, the gears of eachgroup having similar internal clutch teeth, a pair of concentric gearselector members, one for each of said groups of gears, each of saidgear selector members having a set of clutch teeth and being axiallyshiftable within said opening f or selective engagement of its set ofclutch teeth with the clutch teeth of its associated group of gears,and'a pair of clutches co-axial with said gears, said clutchesbeingalternately engageable to connect the drive through one or theother of said gear selector members. 7. In a multi-speed transmission, adriving shaft a driven shaft, a pair of gear sets each providing aplurality of speed ratios between said 'shafts, a pair. of speed-ratioshift members each,

respectively bing shiftable to vary the speed ratio provided by one ofsaid gear sets, a pair of clutch members adapted to be alternatelyengaged for the transmission of load through one or the other of saidgear sets, andspeed-ratio control means comprising a movable memberhaving a plurality 1 of speed ratio positions, cam means and valve gearseach providing a different transmission speed-ratio and beingarrangediwith, the gears providing the even and odd numbered speedratios respectively grouped together, the gears of each group havingsimilar internalclutch teeth, and a pair of concentric gear selectormembers, one

' for each of said groups of gears, each of said gear selector membershaving a set ot'clutch teeth and means jointly movable by said movablemember,

said cam and valve means being so arranged that,

upon movement of said movable member for one speed-ratio position to thenext, said cam means efi'ects movement of the shift member associatedwith the then unloaded gear set while load is being transmitted througha gear of the other gear set, thereafter said valve means beingeflective to control" the application of fluid pressure to said clutchmembers so as to effect engagement of thepreviously disengaged clutchmemher and disengagement of the previously engaged clutch member. 1

8. In a multi-s'peed transmission, a plurality of .co-axial gearsdisposed in side-by-s'ide relation,

- members, and a gear shift control device comprising cam meansandvalve. means so arrangedthat, upon movement of said control meansfrom one speed-ratio position to the next, said cam means first effectsshift movement of the then unloaded gear selector member into engagementwith a selected gear while load is being transmitted through the othergear selector member, then said valve means is rendered operative tocontrol the application of fluid pressure to said clutches to engage thepreviously disengaged clutch and to disengage the previously engaged vclutch and then-said cam means effects1shift movement of the previouslyloaded selector memher out from engagement with the previously selectedgear.

9. In a multi-speed transmission, a plurality of" co-axial gearsdisposed in side-by-side relation,

said gears each providing a different transmission speed ratio and beingarranged with the gears providing the even and odd numbered speed ratios5 respectively grouped together/ thegears of eachv 344,826, publishedMay 4, 1943, class 74/330.

group having similar 14, clutohteeth, a pair of concentric gear selectormembers, one for each group of gears, each of said gear selector membershaving a set of clutch teeth and each being axially shiftable forselective engagement of its set of clutch teeth with the clutch teeth ofits associated group of gears, and'a pair. of clutches alternatelyengageable to provide a drive through 'one or the other of said gearengaging clutches.

ROLAND CHILTON; REFERENCES CITED The following references are of recordin the -file of this patent: j v UNITED STATES PATENTS Number Name 7Date 1,861,008 Hayes May 31, 1932 2,252,644, Robin et a1) Aug 12, 19412,247,715 Peterson et a1. July 1, 1941 2,238,723 Fishburn --L Apr. 15,1941 2,202,378 Hertrich 1 May 28, 1940 2,315,808 Miller Apr. 6, 1943 1802,489 Baerbalck Oct. 24, 1905 1,133,925 Burt Mar. 30, 1915 1,564,767Eggart Dec. 8, 1925 FOREIGN PATENTS' Number Country Date 153,993Austrian Aug. 10, 1938 483,069 British July 6, 1936 OTHER REFERENCES-Kegresse (A. ,P. Qipublication), Serial No.

